"Ms. Vidal asserted today the U.S. government is 'lying' about Alan Gross's health. That is an absurd statement," Gensler said. "The easiest way this could be immediately put to rest is to allow an independent medical doctor to conduct a thorough examination of Mr. Gross."

Monday was the third anniversary of Gross's imprisonment in Cuba. Gross's wife, Judy, and Gensler have waged an increasingly public battle to free him. Last month, they sued the U.S. government and Gross's company, Development Alternatives, Inc., which was fulfilling a State Department contract to set up Internet networks on the island.

The suit said Gross was sent to Cuba without proper training or even basic knowledge of Spanish.

Vidal said Cuba wanted to negotiate "a solution" to Gross's case as well as the return of five Cuban intelligence agents being held in the United States.

She said Cuba has not received an answer from Washington about holding talks on a possible prisoner swap.

U.S. officials have said that Gross is being held hostage and that Cuba should release him immediately.